Diamond Search Site:PriceScope.com is a site that lets you compare the prices of over 350,000 diamonds from retail and Internet vendors. All you need to do is type in the specifics of what you're looking for, and it'll take you to a full list of retailers, which you can filter through by city.

Diamond Wholesalers: Internet retailers like BlueNile.com or WhiteFlash.com don't have to pay the price of having a brick and mortar store, which lowers a lot of their overhead costs. That in turns lowers your cost too!

Brand Sites: Although you'll be paying much more for the brand, perhaps buying a ring from a well-known retailer will give you peace of mind, and you won't have to worry about the quality. Check out sites like Tiffany.com, or if you're looking for less costly options, you can also take a look at Zales.com.